How can I automate senthil.com 's pointing to senthil.travelR.com programatically.
Earlier answer mentioning myDNS helps. up voted
1. How does senthil.com get to my server 2. How does my server know what to do with senthil.com
1. Can only be done by the domain owner. You need to instruct them to either: a) Point the domain to your nameservers (in which case you'll need to configure a DNS server, in this case the myDNS suggestion is a good one). or
b) Have the domain owner setup an A record, pointing to our servers IP address (I assume you already have a dedicated IP - you'll need one).
Question 2, how does your server know what to do with it's traffic?
Well HTTP includes a HOST Header, which represent the hostname the user types into their URL bar.
You'll need to look for this, and direct them to the appropriate mini-site.
One way, as someone pointed out, is using Apache. So, you could either write out apache conf files and trigger reloads, or write some code in your app that looks at this header.
Hope this helps.